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Use crossplat vectors in GetPointerToFirstInvalidChar #90373

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Aug 11, 2023
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Use crossplat vectors in GetPointerToFirstInvalidChar #90373

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16 changes: 16 additions & 0 deletions src/libraries/System.Private.CoreLib/src/System/Runtime/Intrinsics/Vector128.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3221,5 +3221,21 @@ internal static Vector128<byte> SubtractSaturate(Vector128<byte> left, Vector128
}
return AdvSimd.SubtractSaturate(left, right);
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
[CompExactlyDependsOn(typeof(AdvSimd.Arm64))]
[CompExactlyDependsOn(typeof(Sse2))]
internal static Vector128<ushort> AddSaturate(Vector128<ushort> left, Vector128<ushort> right)
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To be exposed as a public API with #82559

{
if (Sse2.IsSupported)
{
return Sse2.AddSaturate(left, right);
}
else if (!AdvSimd.Arm64.IsSupported)
{
ThrowHelper.ThrowNotSupportedException();
}
return AdvSimd.AddSaturate(left, right);
}
}
}
87 changes: 9 additions & 78 deletions src/libraries/System.Private.CoreLib/src/System/Text/Unicode/Utf16Utility.Validation.cs
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Expand Up @@ -63,83 +63,44 @@ internal static unsafe partial class Utf16Utility
// ARM64-intrinsicified code paths. ARM64 platforms may still use the vectorized
// non-intrinsicified 'else' block below.

if (/* (AdvSimd.Arm64.IsSupported && BitConverter.IsLittleEndian) || */ Sse41.IsSupported)
if (/* (AdvSimd.Arm64.IsSupported && BitConverter.IsLittleEndian) || */ Sse2.IsSupported)
{
if (inputLength >= Vector128<ushort>.Count)
{
Vector128<ushort> vector0080 = Vector128.Create((ushort)0x0080);
Vector128<ushort> vector7800 = Vector128.Create((ushort)0x7800);
Vector128<ushort> vectorA000 = Vector128.Create((ushort)0xA000);

Vector128<byte> bitMask128 = BitConverter.IsLittleEndian ?
Vector128.Create(0x80402010_08040201).AsByte() :
Vector128.Create(0x01020408_10204080).AsByte();

char* pHighestAddressWhereCanReadOneVector = pEndOfInputBuffer - Vector128<ushort>.Count;
Debug.Assert(pHighestAddressWhereCanReadOneVector >= pInputBuffer);

do
{
Vector128<ushort> utf16Data;
if (AdvSimd.Arm64.IsSupported)
{
utf16Data = AdvSimd.LoadVector128((ushort*)pInputBuffer); // unaligned
}
else
{
utf16Data = Sse2.LoadVector128((ushort*)pInputBuffer); // unaligned
}
Vector128<ushort> utf16Data = Vector128.Load((ushort*)pInputBuffer);

pInputBuffer += Vector128<ushort>.Count; // eagerly bump this now in preparation for next loop, will adjust later if necessary
Vector128<ushort> charIsNonAscii;

// Sets the 0x0080 bit of each element in 'charIsNonAscii' if the corresponding
// input was 0x0080 <= [value]. (i.e., [value] is non-ASCII.)

if (AdvSimd.Arm64.IsSupported)
{
charIsNonAscii = AdvSimd.Min(utf16Data, vector0080);
}
else
{
charIsNonAscii = Sse41.Min(utf16Data, vector0080);
}
Vector128<ushort> charIsNonAscii = Vector128.Min(utf16Data, vector0080);

#if DEBUG
// Quick check to ensure we didn't accidentally set the 0x8000 bit of any element.
uint debugMask;
if (AdvSimd.Arm64.IsSupported)
{
debugMask = GetNonAsciiBytes(charIsNonAscii.AsByte(), bitMask128);
}
else
{
debugMask = (uint)Sse2.MoveMask(charIsNonAscii.AsByte());
}
uint debugMask = charIsNonAscii.AsByte().ExtractMostSignificantBits();
Debug.Assert((debugMask & 0b_1010_1010_1010_1010) == 0, "Shouldn't have set the 0x8000 bit of any element in 'charIsNonAscii'.");
#endif // DEBUG

// Sets the 0x8080 bits of each element in 'charIsNonAscii' if the corresponding
// input was 0x0800 <= [value]. This also handles the missing range a few lines above.

Vector128<ushort> charIsThreeByteUtf8Encoded;
uint mask;

// Since 3-byte elements have a value >= 0x0800, we'll perform a saturating add of 0x7800 in order to
// get all 3-byte elements to have their 0x8000 bits set. A saturating add will not set the 0x8000
// bit for 1-byte or 2-byte elements. The 0x0080 bit will already have been set for non-ASCII (2-byte
// and 3-byte) elements.

if (AdvSimd.Arm64.IsSupported)
{
charIsThreeByteUtf8Encoded = AdvSimd.AddSaturate(utf16Data, vector7800);
mask = GetNonAsciiBytes(AdvSimd.Or(charIsNonAscii, charIsThreeByteUtf8Encoded).AsByte(), bitMask128);
}
else
{
charIsThreeByteUtf8Encoded = Sse2.AddSaturate(utf16Data, vector7800);
mask = (uint)Sse2.MoveMask(Sse2.Or(charIsNonAscii, charIsThreeByteUtf8Encoded).AsByte());
}
Vector128<ushort> charIsThreeByteUtf8Encoded = Vector128.AddSaturate(utf16Data, vector7800);
uint mask = (charIsNonAscii | charIsThreeByteUtf8Encoded).AsByte().ExtractMostSignificantBits();

// Each even bit of mask will be 1 only if the char was >= 0x0080,
// and each odd bit of mask will be 1 only if the char was >= 0x0800.
Expand Down Expand Up @@ -173,14 +134,8 @@ internal static unsafe partial class Utf16Utility
//
// Since surrogate code points are [D800..DFFF], adding {A000} to each element moves surrogate
// code points to [7800..7FFF], which allows performing a single signed comparison.
if (AdvSimd.Arm64.IsSupported)
{
mask = GetNonAsciiBytes(AdvSimd.CompareLessThan(AdvSimd.Add(utf16Data, vectorA000).AsInt16(), vector7800.AsInt16()).AsByte(), bitMask128);
}
else
{
mask = (uint)Sse2.MoveMask(Sse2.CompareLessThan(Sse2.Add(utf16Data, vectorA000).AsInt16(), vector7800.AsInt16()).AsByte());
}

mask = Vector128.LessThan((utf16Data + vectorA000).AsInt16(), vector7800.AsInt16()).AsByte().ExtractMostSignificantBits();

FinishIteration:

Expand Down Expand Up @@ -221,15 +176,7 @@ internal static unsafe partial class Utf16Utility
// Since 'mask' already has 00 in these positions (since the corresponding char
// wasn't a surrogate), "mask AND mask2 == 00" holds for these positions.

uint mask2;
if (AdvSimd.Arm64.IsSupported)
{
mask2 = GetNonAsciiBytes(AdvSimd.ShiftRightLogical(utf16Data, 3).AsByte(), bitMask128);
}
else
{
mask2 = (uint)Sse2.MoveMask(Sse2.ShiftRightLogical(utf16Data, 3).AsByte());
}
uint mask2 = Vector128.ShiftRightLogical(utf16Data, 3).AsByte().ExtractMostSignificantBits();

// 'lowSurrogatesMask' has its bits occur in pairs:
// - 01 if the corresponding char was a low surrogate char,
Expand Down Expand Up @@ -487,21 +434,5 @@ internal static unsafe partial class Utf16Utility
scalarCountAdjustment = tempScalarCountAdjustment;
return pInputBuffer;
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
[CompExactlyDependsOn(typeof(AdvSimd.Arm64))]
private static uint GetNonAsciiBytes(Vector128<byte> value, Vector128<byte> bitMask128)
{
Debug.Assert(AdvSimd.Arm64.IsSupported);

Vector128<byte> mostSignificantBitIsSet = AdvSimd.ShiftRightArithmetic(value.AsSByte(), 7).AsByte();
Vector128<byte> extractedBits = AdvSimd.And(mostSignificantBitIsSet, bitMask128);

// self-pairwise add until all flags have moved to the first two bytes of the vector
extractedBits = AdvSimd.Arm64.AddPairwise(extractedBits, extractedBits);
extractedBits = AdvSimd.Arm64.AddPairwise(extractedBits, extractedBits);
extractedBits = AdvSimd.Arm64.AddPairwise(extractedBits, extractedBits);
return extractedBits.AsUInt16().ToScalar();
}
}
}